Sartor O, Heinrich D, Mariados N, et al. - Researchers reported the safety and efficiency findings from a 2-year follow-up of the radium-223 re-treatment study. Patients (n = 44) with castration-resistant prostate cancer (CRPC) and bone metastases who finished six initial radium-223 injections with no disease progression in bone and later progressed were suitable for radium-223 re-treatment. Overall, 44 patients were re-treated with radium-223, 29 finished all 6 injections, and 34 entered the 2-year active follow-up, during which no new safety concerns and no serious drug-related adverse events were observed. In 19 of 44 patients, radiographic progression-free survival (rPFS) events (progression or death) occurred and median rPFS was 9.9 months. In 5 of 44 patients, radiographic bone progression occurred. Median OS was 24.4 months. To first symptomatic skeletal event (SSE) and SSE-free survival, median times were 16.7 and 12.8 months, respectively. The median time to total ALP progression was not reached and the median time to prostate-specific antigen progression was 2.2 months. In conclusion, in this selected patient population, re-treatment with radium-223 was well tolerated, which resulted in minimal hematologic toxicity, and gave persistent disease control in the bone at a 2-year follow-up.